Exhaust gas recirculating system control

ABSTRACT

A portion of the engine exhaust gases are connected to the engine air cleaner through valving that is opened to permit recirculation in response to normal accelerating levels of engine spark port intake manifold vacuum, and is closed to terminate recirculation upon a buildup in exhaust gas back pressure acting on the valving.

United States Patent [191 Vartanian EXHAUST GAS RECIRCULATING SYSTEMCONTROL [75] Inventor: Richard D. Vartanian, Dearborn,

Mich.

[73] Assignee: Ford Motor Company, Dearborn,

Mich.

[22] Filed: July 1, 1971 [21] Appl. No.: 158,755

52 U.S.Cl 123/119 A, 55/419, 55/420,

55/010. 28, 137/540 51 Int. Cl. ..F02m 25/06 '[58] FieldofSearch..55/314,419,41s,

55/510, DIG. 28; 123/119 R, 119 A, 119 B, v 122 D; 137/540 1 June 26,1973 2,543,194 2/1951 Paris, Jr. 123/119 A 3,313,281 4/1967 Schneider123/119 8 3,368,345 2/1968 Walker 123/119 B X 3,450,119 6/1969Sendelback. 123/122 D 3,459,163 8/1969 Lewis 123/122 D 3,662,722 5/1972Sarto 123/119 A 3,677,239 7/1972 Elkins 123/119 A Primary ExaminerDennisE. Talbert, Jr.

Attorney-Keith L. Zerschling and Robert E. Mc- Collum [57] ABSTRACT Aportion of the engine exhaust gases are connected to the engine aircleaner through valving that is opened to permit recirculation inresponse to normal accelerating levels of engine spark port intakemanifold vacuum, and is closed to terminate recirculation upon a buildupin exhaust gas back pressure acting on the valving.

10 Claims, 3 Drawing Figures [56] A References Cited UNITED STATESPATENTS 2,408,846 10/1946 Golden et a1. 123/119 A PAIENIEDmzs 191a INVENTOR w mm M w m 7% 0 MM. M

EXHAUST GAS RECIRCULATING SYSTEM CONTROL This invention relates, ingeneral, to an internal combustion engine, and more particularly to anapparatus for controlling the recirculating of engine exhaust gases backinto the engine through the air cleaner.

The recirculation of exhaust gases into an engine reduces the amount ofunburned hydrocarbons and other undesirable elements that mightotherwise pass into the atmosphere, and also redcues the oxygenavailability to thereby lower the peak combustion temperatures andpressure and, therefore, oxides of nitrogen.

The recirculation of exhaust gases into the engine The recirculating ofthe exhaust gases of an internal combustion engine is known. However,the prior art devices generally recirculate these gases into the intakemanifold below the carburetor. This method of recirculation, however,does not permit the unburned hydrocarbons to pass through the meteringsystem of the carburetor, and, accordingly, an accurate measurement ofthe exact fuel-air volume cannot always be made.

This invention obviates the above disadvantage by providing a connectionof the exhaust gases to the air cleaner of the engine, with appropriatevalving, to schedule the recirculation of exhaust gases into the engineat the most appropriate times.

The invention provides a valving that is controlled at times in responseto variations in engine intake manifold vacuum to schedule the flow ofexhaust gases into the air cleaner to occur during acceleration modes ofoperation, when the greatest quantity of oxides of ni-, trogen generallyare generated.

It is a primary object of the invention, therefore, to provide an engineexhaust gas recirculating system to recirculate warm exhaust gasesthrough the air cleaner by means of appropriate valving that schedulesthe flow during desired periods of operation.

It is another object of the invention to provide an engine exhaust gasrecirculating system with valving that permits the flow of exhaust gasesinto the air cleaner of the engine in response to predetermined levelsof operation of the engine intake manifold vacuum, a buildup in exhaustgas pressure level terminating the recirculation.

It is a still further object of the invention to provide an exhaust gasrecirculating system that includes an exhaust gas duct connected to thefresh air inlet of the air cleaner, the flow of exhaust gases beingcontrolled by a first door-type valve that is controlled in its movementby an engine intake manifold vacuum controlled servo, and an overridingvalving for closing the duct when the exhaust gas pressure has risen toa predetermined level.

Other objects, features and advantages of the invention will become moreapparent upon reference to the succeeding detailed description thereof,and to the drawings illustrating a preferred embodiment thereof;

wherein,

FIG. 1 illustrates, schematically, a side elevational view, with partsbroken away and in section, of an engine air inlet supply systemincorporating the invention;

FIG. 2 is an enlarged view of a portion of the FIG. 1 showing, withparts broken away and in section, illustrating the valving of theinvention in one operative position; and

FIG. 3 is a view of a portion of the FIG. 2 showing, illustrating thevalving in a different operative position.

FIG. 1 shows the air inlet supply system for an internal combustionengine indicated schematically at 10. The latter has mounted on it adowndraft type carburetor indicated at 12, upon which is mounted a knowntype of dry element type air cleaner 14. Further details of constructionand operation of the carburetor and engine per se are not given sincethey are known, and are believed to be unnecessary for an understandingof the invention. Suffice it to say, however, that the carburetorgenerally would have a venturi type induction passage or bore 15 open atits lower end to the intake manifold of engine 10, and an upper endopening into the air cleaner outlet (not shown) to receive therein aclean supply of fresh air. In this case, the outlet would also receivethe exhaust gases recirculated in a manner to be described. Flow throughthe passage 15 would be controlled in a known manner by a rotatablymounted throttle valve 16.

As stated, the air cleaner 14 generally consists of a lower hollow traysection or pan 17 having a central outlet to the carburetor described,and enclosed at its top by a cover 18. It would contain, in general,anannular pleated paper or similar type dry element air filter thatwould clean any air or fluid that passes therethrough from an air inletopening 20 in one side thereof.

More specifically, the air inlet 20 receives therein the end of asnorkel type air duct 22, only a portion of which is shown. This ductcan be of the construction shown and described fully in U.S. Pat. No.3,450,119, R.E. Sendelbach. For clarity, the details,except for theinvention, are omitted. Suffice it to say that the air inlet snorkel 22generally would have a bifurcated air inlet in which one portion of theduct receives fresh air from the vehicle engine compartment through theflared inlet 23, and the other portion of the duct receives air heatedby passage over a stove, such as the exhaust manifold stove. A movablevalve would control the proportion of fresh, colder air to exhaust stoveair through the air cleaner into the engine as a function of operatingtemperatures and manifold vacuum, as more fully explained'in U.S. Pat.No. 3,450,119.

Turning now to the invention, as more clearly shown in FIG. 2, a hollowtube 24 opens into duct 22 at essentially right angles thereto. The tube24 consists of an inverted cup-shaped sleeve 25 in which is fixed in itsopen lower inlet end a conduit 26 containingexhaust gases from theexhaust manifold or system. At its other upper end, sleeve 25 has acircular opening or outlet 27 adapted to be closed by a hat-shaped orbutton type valve member or valve 28. The valve 28 forms one part of anoverall valve means that controls the flow of exhaust gases from tube 24into air duct 22 and inlet 20. A second part of the valve means is acup-shaped valve member or valve 30 slidably movable within duct tube24. The inner diameter of valve member 30 is of greater diameter thanvalve member 28 so as to slidably receive the latter therein in atelescopic manner. The

outer diameter of the walls of valve member 30 is of less diameter thanthe inner diameter of sleeve so as to provide a passage 31 for flow ofexhaust gases between the two portions. A compression spring 32 biasesthe two valve members 28 and apart, urging valve member 28 to seatagainst the bottom of sleeve 25 and the end 33 of valve member 30 toseat against the end of the exhaust gas conduit 26. In this. manner,valve member 28 normally blocks off the passage of exhaust gases outinto the air cleaner duct 22. The base 33 of second valve member 30 isslotted diagonally at 34 so as to always permit a flow of exhaust gasesinto passage 31 between valve member 30 and sleeve 24.

The force of spring 32 is chosen such as to normally position the partsas shown in FIG. 2, but, however, permitting a movement of valve member30 to the position shown in FIG. 3 upon a suitable increase in thepressure of the exhaust gases acting against the bottom of valve member30. In this way, a buildup of exhaust gas pressure will seat the secondvalve member 30 against the upper end of sleeve 25 and block the flow ofexhaust gases into the air cleaner under these conditions.

Completing the construction, the first valve member 28 is adapted to bemoved downwardly to open the exhaust gas duct to the air cleaner bymeans of a stem type actuator 40. The latter is attached to a plate 42pivoted at 44 to a portion of duct 22. The plate 42 in turn is swungvertically by a vacuum controlled servo 46 of a known diaphragm type.That is, the servo body 48 is hollow and contains a flexible annulardiaphragm 50 dividing the housing into an atmospheric air chamber 52 anda vacuum chamber 54. The diaphragm is connected to plate 42 by asuitable link 56. A compression spring 58 normally biases the diaphragmto the upward position shown holding door 42 and actuator 40 in the fullline position shown.

A vacuum line 60 is connected to chamber 54, and is adapted to beconnected at its opposite end to the intake manifold of the engine so asto subject chamber 54 to changing intake manifold vacuum levels. In thiscase, to assure recirculation of exhaust gases only during theacceleration periods desired, as mentioned above, vacuum line 60 isconnectedto the spark port 62 of the carburetor located just above theidle speed position of throttle valve 16. Thus, when the throttle valveis closed, as shown, during engine idle speed operations, no vacuum willexist in line 60; i.e. atmospheric pressure will be present permittingspring 58 to position the plate door 42 and actuator 40 as shown. Atengine wide open throttle positions, wherein the throttle valve 16 isnearly vertical, initially the engine intake manifold vacuum will bevery low, i.e., the pressure will be nearly atmospheric again causingthe servo to position to the plate door 42 as shown.

if desired, a further on-off control, indicated by the block 59, couldbe provided in line 60, and would be speed responsive so that, forexample, below a speed of sayd 28 m.p.h., for example, line 60 would beblocked, thereby rendering the servo ineffective below 28 m.p.h. to moveplate 42 and permit exhaust recirculation.

In operation, as stated above, the primary object of the invention is tocontrol exhaust gas recirculation to be effective essentially during theacceleration mode of operation so that the exhaust gases are notrecirculated during engine idle operating conditions nor at engine .wideopen throttle conditions. This is effectively obtained by the use ofintake manifold vacuum and exhaust back pressure as controls and/oralternatively combined with a vehicle speed responsive control.

In brief, prior to engine start up, the parts are in the position shownin which actuator 40 is maintained out of contact with valve member 28by means of spring 58. Upon engine start up, at engine idle speedcondition, the spark port vacuum is essentially atmospheric pressurepermitting vacuum servo spring 58 to maintain valve actuator 40 in theposition shown. During a part throttle condition of acceleration, thespark port vacuum in port 62 will increase, thereby increasing thevacuum level in servo chamber 54 and causing plate valve 42 with itsactuator 40 to move down to the dotted line position against and moveopen valve member 28. This permits exhaust gas to pass through passage31 and out into the air cleaner snorkel duct 22 to be recirculated intothe engine. This latter operation assumes that the vehicle speed isabove 28 m.p.h., if a vehicle speed responsive switch 59 is used.

During the acceleration mode, the exhaust back pressure in conduit 26will slowly increase until the point is reached where the force actingagainst the bottom of valve member 30 is sufficient to compress spring32 and move valve member 30 upwardly to seat and close off passage 26.This shuts off the recirculation of exhaust gases into the air cleaner,regardless of the position of valve member 28.

During wide open throttle operation, the decay of spark port vacuum toessentially atmospheric pressure in servo chamber 54 permits spring 58to maintain plate 42 in the full line position shown, comparable to theengine idle speed operating condition, or to the position below avehicle speed of 28 m.p.h. No exhaust gas recirculation, therefore,occurs at this time.

From the foregoing, it will be seen that the invention provides aneffective exhaust gas recirculation system to recirculate the exhaustgases into the engine during the acceleration modes of operation, whileeffectively preventing the recirculation during engine idle and wideopen throttle conditions of operation of the engine, or duringdeceleration, and alternatively, below a vehicle speed of apredetermined level of, say, 28 m.p.h.

I claim:

1. A system for recirculating exhaust gases from the exhaust manifold ofan internal combustion engine back into said engine through the aircleaner thereof, said air cleaner comprising a housing having an outletto the carburetor of said engine and a fresh air inlet, a conduitcontaining exhaust manifold gases operatively connected to said inlet,first means variably movable between positions opening and closing saidconduit to control the flow of exhaust gas into said air cleaner andcarburetor, vacuum power means controlled in response to variations inengine intake manifold vacuum to move said first means between saidpositions, second valve means controlling the flow of exhaust gases outof said conduit, and spring means biasing said second valve means to aposition closing saidgas conduit, said first means moving said secondvalve means to open said gas conduit.

2. A system as in claim 1, said second valve means having a firstpassage connected at all times to said exhaust gases, a movable valvemember biased by said spring means to a position closing said passage,said first means engaging said valve member and moving said valve memberto open said passage at times to said air inlet, an increase in pressureof said exhaust gases above a predetermined level effecting a closing ofsaid passage.

3. A system as in claim 1, said second valve means being acted upon bysaid gases and movable above a predetermined pressure thereof in adirection to close said gas conduit to terminate flow of said gases intosaid air cleaner.

4. A system as in claim 3, said second valve means including a secondvalve member movable by said exhaust gases acting thereagainst to closesaid passage.

5. A system as in claim 4, said spring means being positioned betweensaid first and second valve members.

6. A. system for recirculating exhaust gases from the exhaust manifoldof an internal combustion engine back into said engine through the aircleaner thereof, said air cleaner comprising a housing having an outletto the carburetor of said engine and a fresh air inlet, a conduitcontaining exhaust manifold gases and operatively connected to saidinlet, first means variably movable between positions opening andclosing said conduit to control the flow of exhaustgas into said. aircleaner inlet to the carburetor, vacuum power means controlled inresponse to variations in engine intake manifold vacuum to movesaid'first means between said positions, second valve means controllingthe flow of exhaust gases out of said conduit, said second valve meansincluding a valve body defined by the conduit having a gas inlet andoutlet and a gas passage therebe tween, said gas inlet containing saidexhaust gases and said gas outlet being operatively connected to saidair inlet, first and second valve members movably associatedrespectively with said gas outlet and gas inlet,

spring means between said valve members biasing said members to seatedpositions against said gas inlet and gas outlet closing said gas outlet,said first means in its movement engaging said first valve member tomove said first valve member to open said gas outlet, a rise in exhaustgas pressure above a predetermined level moving said second valve memberto close said gas outlet.

7. A system as in claim 6, said second valve member including gas bypassmeans permitting bypass of exhaust gases through said gas inlet pastsaid second valve member.

9. A system as in claim 6, said second valve member including meansengagable with said valve body to close said passage regardless of theposition of said first valve member.

8. A system as in claim 6, said first valve member having essentially adisc-like shape, said second valve member having essentially a U-shapereceiving the first valve member at times in the open end thereof.

10. A system as in claim 9, the legs of said second to close saidpassage.

1. A system for recirculating exhaust gases from the exhaust manifold ofan internal combustion engine back into said engine through the aircleaner thereof, said air cleaner comprising a housing having an outletto the carburetor of said engine and a fresh air inlet, a conduitcontaining exhaust manifold gases operatively connected to said inlet,first means variably movable between positions opening and closing saidconduit to control the flow of exhaust gas into said air cleaner andcarburetor, vacuum power means controlled in response to variations inengine intake manifold vacuum to move said first means between saidpositions, second valve means controlling the flow of exhaust gases outof said conduit, and spring means biasing said second valve means to aposition closing said gas conduit, said first means moving said secondvalve means to open said gas conduit.
 2. A system as in claim 1, saidsecond valve means having a first passage connected at all times to saidexhaust gases, a movable valve member biased by said spring means to aposition closing said passage, said first means engaging said valvemember and moving said valve member to open said passage at times tosaid air inlet, an increase in pressure of said exhaust gases above apredetermined level effecting a closing of said passage.
 3. A system asin claim 1, said second valve means being acted upon by said gases andmovable above a predetermined pressure thereof in a direction to closesaid gas conduit to terminate flow of said gases into said air cleaner.4. A system as in claim 3, said second valve means including a secondvalve member movable by said exhaust gases acting thereagainst to closesaid passage.
 5. A system as in claim 4, said spring means beingpositioned between said first and second valve members.
 6. A system forrecirculating exhaust gases from the exhaust manifold of an internalcombustion engine back into said engine through the air cleaner thereof,said air cleaner comprising a housing having an outlet to the carburetorof said engine and a fresh air inlet, a conduit containing exhaustmanifold gases and operatively cOnnected to said inlet, first meansvariably movable between positions opening and closing said conduit tocontrol the flow of exhaust gas into said air cleaner inlet to thecarburetor, vacuum power means controlled in response to variations inengine intake manifold vacuum to move said first means between saidpositions, second valve means controlling the flow of exhaust gases outof said conduit, said second valve means including a valve body definedby the conduit having a gas inlet and outlet and a gas passagetherebetween, said gas inlet containing said exhaust gases and said gasoutlet being operatively connected to said air inlet, first and secondvalve members movably associated respectively with said gas outlet andgas inlet, spring means between said valve members biasing said membersto seated positions against said gas inlet and gas outlet closing saidgas outlet, said first means in its movement engaging said first valvemember to move said first valve member to open said gas outlet, a risein exhaust gas pressure above a predetermined level moving said secondvalve member to close said gas outlet.
 7. A system as in claim 6, saidsecond valve member including gas bypass means permitting bypass ofexhaust gases through said gas inlet past said second valve member.
 8. Asystem as in claim 6, said first valve member having essentially adisc-like shape, said second valve member having essentially a U-shapereceiving the first valve member at times in the open end thereof.
 9. Asystem as in claim 6, said second valve member including means engagablewith said valve body to close said passage regardless of the position ofsaid first valve member.
 10. A system as in claim 9, the legs of saidsecond valve member defining with said valve body the said passage, saidlegs being engagable with said valve body to close said passage.